// @flow
import React from 'react';
import { withRouter } from 'react-router-dom';
import queryString from 'query-string';
import compose from 'recompose/compose';
import getThreadMessages, {
  type GetThreadMessageConnectionType,
} from 'shared/graphql/queries/thread/getThreadMessageConnection';
import { sortAndGroupMessages } from 'shared/clients/group-messages';
import NextPageButton from 'src/components/nextPageButton';
import viewNetworkHandler, {
  type ViewNetworkHandlerType,
} from 'src/components/viewNetworkHandler';
import ChatMessages from 'src/components/messageGroup';
import { Loading } from 'src/components/loading';
import NullMessages from './nullMessages';
import type { Location } from 'react-router';
import { NullMessagesWrapper } from '../style';

type Props = {
  // Used by getThreadMessages query
  isWatercooler: boolean,
  data: {
    loading: boolean,
    thread: ?GetThreadMessageConnectionType,
  },
  loadPreviousPage: Function,
  loadNextPage: Function,
  onMessagesLoaded?: Function,
  location: Location,
  thread?: Object,
  ...$Exact<ViewNetworkHandlerType>,
};

class Messages extends React.Component<Props> {
  componentDidMount() {
    const thread = this.props.data.thread || this.props.thread;
    // Scroll to bottom on mount if we got cached data as getSnapshotBeforeUpdate does not fire for mounts
    if (thread && thread.watercooler) {
      const elem = document.getElementById('main');
      if (!elem) return;
      elem.scrollTop = elem.scrollHeight;
    }
  }

  getSnapshotBeforeUpdate(prev) {
    const curr = this.props;
    // First load
    if (!prev.data.thread && curr.data.thread && curr.data.thread.watercooler) {
      return {
        type: 'bottom',
      };
    }
    // New messages
    if (
      prev.data.thread &&
      curr.data.thread &&
      prev.data.thread.messageConnection.edges.length > 0 &&
      curr.data.thread.messageConnection.edges.length > 0 &&
      prev.data.thread.messageConnection.edges.length <
        curr.data.thread.messageConnection.edges.length
    ) {
      const elem = document.getElementById('main');
      if (!elem || !curr.data.thread) return null;

      // If new messages were added at the top, persist the scroll position
      if (
        prev.data.thread.messageConnection.edges[0].node.id !==
        curr.data.thread.messageConnection.edges[0].node.id
      ) {
        return {
          type: 'persist',
          values: {
            top: elem.scrollTop,
            height: elem.scrollHeight,
          },
        };
      }

      // If more than one new message was added at the bottom, stick to the current position
      if (
        prev.data.thread.messageConnection.edges.length + 1 <
        curr.data.thread.messageConnection.edges.length
      ) {
        return null;
      }

      // If only one message came in and we are near the bottom when new messages come in, stick to the bottom
      if (elem.scrollHeight < elem.scrollTop + elem.clientHeight + 400) {
        return {
          type: 'bottom',
        };
      }

      // Otherwise stick to the current position
      return null;
    }
    return null;
  }

  componentDidUpdate(prevProps, __, snapshot) {
    const { onMessagesLoaded } = this.props;
    // after the messages load, pass it back to the thread container so that
    // it can populate @ mention suggestions
    const prevData = prevProps.data;
    const currData = this.props.data;
    const wasLoading = prevData && prevData.loading;
    const hasPrevThread = prevData && prevData.thread;
    const hasCurrThread = currData && currData.thread;
    const previousMessageConnection =
      // $FlowIssue
      hasPrevThread && prevData.thread.messageConnection;
    const currMessageConnection =
      // $FlowIssue
      hasCurrThread && currData.thread.messageConnection;
    // thread loaded for the first time
    if (!hasPrevThread && hasCurrThread && currMessageConnection) {
      if (currMessageConnection.edges.length > 0) {
        onMessagesLoaded && onMessagesLoaded(currData.thread);
      }
    }
    // new messages arrived
    if (previousMessageConnection && hasCurrThread && currMessageConnection) {
      if (
        currMessageConnection.edges.length >
        previousMessageConnection.edges.length
      ) {
        onMessagesLoaded && onMessagesLoaded(currData.thread);
      }
      // already loaded the thread, but was refetched
      if (wasLoading && !currData.loading) {
        onMessagesLoaded && onMessagesLoaded(currData.thread);
      }
    }

    if (snapshot) {
      const elem = document.getElementById('main');
      if (!elem) return;
      switch (snapshot.type) {
        case 'bottom': {
          elem.scrollTop = elem.scrollHeight;
          return;
        }
        case 'persist': {
          elem.scrollTop =
            elem.scrollHeight - snapshot.values.height + snapshot.values.top;
          return;
        }
        default: {
          return;
        }
      }
    }
  }

  render() {
    const { data, isLoading, isFetchingMore, hasError } = this.props;

    const { thread } = data;
    if (thread && thread.messageConnection) {
      const { messageConnection } = thread;
      const { edges } = messageConnection;

      if (edges.length === 0) return <NullMessages />;

      const unsortedMessages = edges.map(message => message && message.node);
      const sortedMessages = sortAndGroupMessages(unsortedMessages);

      if (!sortedMessages || sortedMessages.length === 0)
        return <NullMessages />;

      return (
        <React.Fragment>
          {messageConnection.pageInfo.hasPreviousPage && (
            <NextPageButton
              isFetchingMore={isFetchingMore}
              fetchMore={this.props.loadPreviousPage}
              automatic={!!thread.watercooler}
              href={{
                pathname: this.props.location.pathname,
                search: queryString.stringify({
                  ...queryString.parse(this.props.location.search),
                  msgsbefore: messageConnection.edges[0].cursor,
                  msgsafter: undefined,
                }),
              }}
            >
              Show previous messages
            </NextPageButton>
          )}
          <ChatMessages
            thread={thread}
            uniqueMessageCount={unsortedMessages.length}
            messages={sortedMessages}
            threadType={'story'}
            isWatercooler={thread.watercooler}
          />
          {messageConnection.pageInfo.hasNextPage && (
            <NextPageButton
              isFetchingMore={isFetchingMore}
              fetchMore={this.props.loadNextPage}
              href={{
                pathname: this.props.location.pathname,
                search: queryString.stringify({
                  ...queryString.parse(this.props.location.search),
                  msgsafter:
                    messageConnection.edges[messageConnection.edges.length - 1]
                      .cursor,
                  msgsbefore: undefined,
                }),
              }}
            >
              Show more messages
            </NextPageButton>
          )}
        </React.Fragment>
      );
    }

    if (isLoading)
      return (
        <NullMessagesWrapper>
          <Loading style={{ height: '80vh' }} />
        </NullMessagesWrapper>
      );

    if (hasError) return null;

    return null;
  }
}

export default compose(
  withRouter,
  getThreadMessages,
  viewNetworkHandler
)(Messages);